Manufacture of hardened-steel projectiles.



U. DAVIS. MANUFACTURE OF HARDENED STEEL PROJEGTILES,

APPLICATION FILED APR. 23, 1902.

9 ?Aj2, Patented Sept. 13,1910.

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UNITED STATES PATENTOFEIGE.

CLELAND DAVIS, OF THE UNITED STATES NAVY ASSIGNOR, BY KESNE ASSIGNMENTS, TO CARNEGIE STEEL COMPANY, OF PITTSBUBG, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

MANUFACTURE OF HARDENED-STEEL EEOJECTILES.

Specification of Letters Patent.

Patented Sept. 13, 1910.

Application filed. April 28,1902. Serial No. 104,381.

" tenant U; S. Navy, a citizen of the United States, stationed at Washington, in the District of Columbia, have invented certain new and useful Improvements in the Manufacture of Hardened-Steel Projectiles, (Case F;) and I' do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Myinvention relates to improvements in processes of hardening steel and while applicable to plates or othermasses of steel of any shape whatever, it' is especially ada ted for use in manufacture of hollow stee projectiles.

The drawings show one embodiment of the invent-ion in the treatment of hollow projectiles.

: Figure 1' represents an elevation part1 in section of a shell being treated accor ing to any inventiomfthe' electrical connections being indicated diagrammatically. Fig. 2 is a similar view showing modified forms of electrodes.

A represents the-shelhhaving the usual cavity A and provided with screw threads a for the bushing not shown.

B represents an electrode, preferably of carbon, which incloses the head of the shell and to'which current is applied by the conductorb. D represents the other electrode, preferably of'copper, which is of shape to make suitable contact with the inner wall of the cavity A" at its forward end. The electrode D may be inserted or removed by the stem at which is connected by a conductor (Z to the opposite pole of the source of electricity, not shown.

The current which may be either direct or alternating passes from one electrode to the other, heating the forward portion of the shell in such a manner as to produce a hardening eifect when the shell is cooled.

here the electrodes are applied to the portions to be hardened the necessary heat is obtained by varying the contact and con-- sequent resistance between the electrode and the body under treatmcnt. Where high temperatures are used, I preferably screen the heated portions from the air while under treatment, as described in my patent No. 687612 granted Nov. 26, 1901.

Since with large shells it might not always be practicable to secure a heavy enough current to heat so large a portion of the shell at the same time, an arrangement similar to that in Fig. 2 may be adopted, in which the louter electrode-is composed of a number of conducting strips 13 insulated from each other and from the holding bands 0. At the v ends of these strips I provide the conducting piece B inclosing the tip of the shell. This piece B and the strips B are connected to the source of electriclty, not shown, by the conductors b and b res ectively. These pieces B and B may be 0 metal or carbon or any other suitable conductor. The inner electrode D may be of carbon secured to the copper stem (2 and connected to the con ductor d. either from the positive pole of the source of electricity through the conductor 1) and b passing out through the conductor 0!; or it may be caused to flow in the opposite direction; or an alternatin current may be used. By cutting in the pieces B B singly or in groups, the front end of the shell may be hardened progressively, that is one part at a time until it is all hardened.

While I have described electrodes of carbon' and copper, any suitable material may be used for the electrodes, and the carbon electrode may be'applied to the outer wall or to the lnner wall'or to both walls of the shell by having one or the other or both electrodes of carbon; moreover the current may be caused to flow in either direction, or an alternating current may be used.

A heavy electric current will quickly bring the part of the shell being treated to the requisite degree of temperature, and the shell may be then chilled either by simply turning olf the current, or by actually removing the electrodes and immersing it in a bath, or by spraying water or blowing air on the shell.

I have shown the shell in an advanced state of manufacture, but it may be treated at any time after the front of the shell has been suitably shaped.

lVhile I have described the invention more especially as applied to the manufacture of hollow projectiles, it will be obvious that any The current may be applied 1 jectiles of steel, that step which consists in v chilling the nose of theplacing an electrode exterior of the nose of the projectile and another electrode in the. cavity in said projectile and passing a heavy current between said electrodes, substantially as described.

2. In the method of hardening hollow projectiles, the steps of applying a carbon elec-' trode to the nose of the projectile, anothercarbon electrode to the inner wall of the pro-' jectile, and passing a heavy current between the said electrodes, substantially as described. v

3. The method of hardening hollow steel. projectiles of high carbon steel which consists in placing an electrode exterior to the nose of the projectile, placing another electrode in the forward part of the cavity of theprojectile, passing a heavy electric current between said electrodes, and subsequently projectile, substantially as described.

4. In the method of hardening hollow projectiles, the steps ofapplying a carbon electrode to the exterior nose of the projectile, applying another electrode in the cavity against the other face of the nose, passin a heavy electric current between said e ectrodes, and driving carbon from the exterior electrode into the steel'point of the projectile, I

substantially as described.

5. The method of hardening hollow pro jectiles consisting in applying a carbon electrode to the exterior nose of the projectile,

applying a second carbon electrode in the electrodes and driving carbon from oneof 'the electrodes into the steel point, then removing the electrodes and cooling the point of the projectile, substantially as described..

6. In the method of hardening holl0w,projectiles, the steps of applying a carbon'electrode to a portion of the nose of the projectile, another electrode in the cavity of the projectile, passing a heavy electric current between said electrodes and shifting the point of application of the carbon electrode, substantially as described.

7 The herein described methodiof hardening hollow projectiles, which consists in applying an electrode within the nose portion of the projectile, and another electrode upon the exteriorofthe nose in imperfect contact therewith, and covering that portion of the nose which is to be hardened, passing a heavy current of electricity through the electrodes and the nose portion of the projectile; shut' ting oli' the current, and thenchilling the described. In testimony whereof, I athx my signature, in presence of two Witnesses.

heated portion of the projectile, substantially 

